Child Process Module

The child_process module allows you to spawn new processes and communicate with them. It provides four different methods for creating child processes:

Methods for Creating Child Processes

exec method is useful for running shell commands.

This method runs a command in a shell and buffers the output. It's suitable for short-lived processes where you need the entire output once the process completes.

import { exec } from 'child_process';

exec('ls -la', (error, stdout, stderr) => {
  if (error) {
    console.error(`exec error: ${error}`);
    return;
  }
  console.log(`stdout: ${stdout}`);
  console.error(`stderr: ${stderr}`);
});

execFile method is used to run a file directly.

This method is similar to exec(), but it directly executes a file without using a shell, making it slightly more efficient and secure.

import { execFile } from 'child_process';

execFile('node', ['--version'], (error, stdout, stderr) => {
  if (error) {
    console.error(`execFile error: ${error}`);
    return;
  }
  console.log(`stdout: ${stdout}`);
  console.error(`stderr: ${stderr}`);
});

spawn method

This method launches a new process with a given command. It is suitable for long-running processes where you need to handle the process's I/O streams (stdout, stderr, stdin) in a non-blocking way.

import { spawn } from 'child_process';

const ls = spawn('ls', ['-la']);

ls.stdout.on('data', (data) => {
  console.log(`stdout: ${data}`);
});

ls.stderr.on('data', (data) => {
  console.error(`stderr: ${data}`);
});

ls.on('close', (code) => {
  console.log(`child process exited with code ${code}`);
});

fork method

This method is designed for spawning new Node.js processes. It has built-in communication channels (IPC) for sending messages between the parent and child processes.

import { fork } from 'child_process';

const child = fork('./child.ts');

child.on('message', (message) => {
  console.log(`Message from child: ${message}`);
});

child.send('Hello from parent process');

Methods for Creating Child Processes​

Methods for Creating Child Processes